21180997 has 8 divisors (see below), whose sum is σ = 22600512. Its totient is φ = 19780800.

The previous prime is 21180949. The next prime is 21181001. The reversal of 21180997 is 79908112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21180997 - 2¹⁹ = 20656709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21180917) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2529 + ... + 6982.

It is an arithmetic number, because the mean of its divisors is an integer number (2825064).

Almost surely, 2^21180997 is an apocalyptic number.

It is an amenable number.

21180997 is a deficient number, since it is larger than the sum of its proper divisors (1419515).

21180997 is a wasteful number, since it uses less digits than its factorization.

21180997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9659.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 21180997 is about 4602.2817167140. The cubic root of 21180997 is about 276.6827814358.

The spelling of 21180997 in words is "twenty-one million, one hundred eighty thousand, nine hundred ninety-seven".